CHEMICAL ECOLOGY – The Chemical Ecology of Mustelids - M. J. Davies THE CHEMICAL ECOLOGY OF MUSTELIDS M. J. Davies Department of Biological Sciences, Hull University, UK Keywords: Mustelid, otter, badger, scent marking, anal sac, sub-caudal gland, territoriality, resource marking. Contents 1. Introduction: what are Mustelids? 2. Scent marking in Mustelids 2.1 The Function of scent marking 2.2 Sources of odor 2.2.1 Urine and Faeces 2.2.2 Skin glands 2.2.3 Scent producing organs. 2.3 The chemistry of scent marking 2.4 Initial work on scent-marking behavior 3. The Eurasian or European Otter (Lutra lutra) 3.1 Introduction 3.2 Difficulties in surveying otter populations. 3.3 Spraints and scent marking behavior. 3.3.1 Seasonal spraint deposition and sexual behavior 3.3.2 Territoriality 3.3.3 Social organization 3.3.4 Resource marking 3.3.5 Individual identity 3.4 Road kill and manipulation of otter movements 3.5 Investigation of gland material 4. The European Badger (Meles meles) 4.1 Introduction 4.2 Badger scent sources. 4.3 Scent marking behavior 4.3.1 Food LocationUNESCO and Detection of danger – EOLSS 4.3.2 Individual and clan identity 4.3.3 Navigation 4.3.4 Territoriality 4.3.5 Social statusSAMPLE CHAPTERS 4.4 Investigation of gland material 4.5 Badgers and Bovine Tuberculosis 5. The Future of Mustelid Chemical Ecology Research Glossary Bibliography Biographical Sketch ©Encyclopedia of Life Support Systems (EOLSS) CHEMICAL ECOLOGY – The Chemical Ecology of Mustelids - M. J. Davies Summary The Mustelidae or weasel family is the largest family in the order of mammals known as the Carnivora with sixty-seven highly specialized species having the ability to exploit a variety of contrasting environments. Mustelids lead complex social lives that require effective transfer of information in order to be maintained. One way of achieving this is through odor, via scent marking. There are a number of theories regarding the exact role played by scent marking behavior (e.g., territorial defense, resource marking, maintenance of social organization/dominance hierarchies, navigation/food location) and regarding types of information conveyed (e.g., reproductive condition, family/clan identity, individual identity). There are a variety of odor sources used by mustelids (e.g., urine/faeces, skin glands, scent producing organs). Therefore odor may be comprised of chemicals provided by undigested food material, chemicals synthesized by the animal or produced by bacteria (scent organs often provide a moist, warm, anaerobic environment favorable for bacterial development). Analytical work carried out investigating the chemical make-up of mustelid scent marks has revealed them to be a complex mix of compounds. Analysis of odor profiles (chemical extraction, separation, quantification and identification) needs to be integrated with behavioral studies in order to pinpoint the active components. Understanding scent marking would allow significant insight into mustelid social behavior and ecology. E.g., this could lead to solutions for both conservation management (many mustelids are threatened with extinction, e.g., the black-footed ferret, Mustela nigripes) and economic problems (e.g., the European badger – a host for bovine tuberculosis?). 1. Introduction: what are Mustelids? The Mustelidae, or weasel family is the largest and most diverse of the 7 families in the order of mammals known as the Carnivora. There are sixty-seven species of Mustelidae (thirteen of which are found in Europe) and these are divided into 5 sub-families: the Mustelinae (stoats, weasels, martens, polecats, wolverines); the Melinae (true badgers); the Mellivorniae (honey badger or ratel); the Mephitinae (skunks); and the Lutrinae (otters). There has often been disagreement over these classifications, but although repeatedly questioned they remain the ‘industry benchmark’. UNESCO – EOLSS SAMPLE CHAPTERS ©Encyclopedia of Life Support Systems (EOLSS) CHEMICAL ECOLOGY – The Chemical Ecology of Mustelids - M. J. Davies Figure1. The weasel (juvenile), Mustela nivalis (Photograph, Dr. Pat Morris, Royal Holloway, University of London) UNESCO – EOLSS SAMPLE CHAPTERS Figure2. The stoat, Mustela erminea (Photograph, Dr. Pat Morris, Royal Holloway, University of London) The Mustelidae therefore contain some well-known species and the success of these species demonstrates the evolutionary principle of adaptive radiation. Early forms of mustelid lived in forests and were less specialized, but as they evolved they diversified into more highly specialized species with the ability to exploit a variety of contrasting environments. ©Encyclopedia of Life Support Systems (EOLSS) CHEMICAL ECOLOGY – The Chemical Ecology of Mustelids - M. J. Davies Western European Mustelids are typically terrestrial, e.g., the weasel (Mustela nivalis), the stoat (Mustela erminea) and the polecat (Mustela putorius) [Figures 1, 2 & 3 respectively]. Figure3. The polecat, Mustela putorius (Photograph, Dr. Pat Morris, Royal Holloway, University of London) UNESCO – EOLSS SAMPLE CHAPTERS Figure4. The wolverine, Gulo gulo (Photograph, Dr. Pat Morris, Royal Holloway, University of London) The larger and less familiar Wolverine, Gulo gulo (Figure 4) has adapted to the harsher conditions found in Northern Europe and America and has been observed to predate upon sheep during the summer months in Norwegian mountain ranges. ©Encyclopedia of Life Support Systems (EOLSS) CHEMICAL ECOLOGY – The Chemical Ecology of Mustelids - M. J. Davies The Pine marten, Martes martes (Figure 5) is mainly arboreal and an adept climber, perfectly at home in the trees of more northern European forests, although in Britain it happily exists in rocky and more open environments. The Pine marten’s closest European cousin is the Beech marten, Martes foina. It has similar adaptations and its range overlaps with that of its cousin, however it does not compete, as it prefers deciduous woodland and more cultivated areas. Additionally, it has a more southerly distribution. Figure5. The pine marten, Martes martes (Photograph, Dr. Pat Morris, Royal Holloway, University of London) UNESCO – EOLSS SAMPLE CHAPTERS Figure6. The sea otter, Enhydra lutris (Photograph, Dr. Pat Morris, Royal Holloway, University of London) Other highly specialized Mustelid species include the otter, which is remarkably adapted to its semi aquatic existence. Examples include the European otter, Lutra lutra (see Section 3, Figure 9), quite at home on land, but only when observed in water do its adaptations to this quite different environment become apparent. In contrast the Sea ©Encyclopedia of Life Support Systems (EOLSS) CHEMICAL ECOLOGY – The Chemical Ecology of Mustelids - M. J. Davies otter, Enhydra lutris (Figure 6) has adapted to an almost completely marine lifestyle, rarely coming ashore. The badger, Meles meles (see Section 4, Figure 10), e.g., is far more omnivorous than other mustelid species, but feeds mostly on a diet of invertebrates. It leads a subterranean existence and can dig out extensive burrow systems allowing long periods to be spent underground. Mustelids have a typically solitary nature (although there are exceptions, e.g., the Giant otter, Pteronura brasiliensis (Figure 7) and individuals are generally territorial. Figure7. The giant otter, Pteronura brasiliensis (Photograph, Dr. Pat Morris, Royal Holloway, University of London) Occasionally,UNESCO more than one species will oc–cur inEOLSS close proximity, and there is some evidence for interference. Generally, mustelids have social organization where females are resident in small ranges within the much wider territory of a male. Sufficient food SAMPLEresources to rear offspring areCHAPTERS the main concern for female mustelids when choosing a home range to occupy. Males will maximize their reproductive output when their territories encompass as many female ranges as possible. Therefore food resources also ultimately determine male ranges. This classical model of intra-sexual territoriality is typical of socio-biological organization in many other mammal families, e.g., Ursidae, Viverridae and Felidae. There are exceptions however, with more social species bucking the trend, unusual not only in mustelids, but also in the Carnivores as a whole. ©Encyclopedia of Life Support Systems (EOLSS) CHEMICAL ECOLOGY – The Chemical Ecology of Mustelids - M. J. Davies Another theory states that mating systems are not an evolved feature of each species, but appear as individual strategies. Mustelid social organization and behavior can be flexible showing variation even within populations. For instance, in Britain badgers typically form clans of up to 12 individuals, comprising both males and females. Elsewhere in their range individuals exhibit intra- and inter-sexual territoriality having either a solitary existence or living in pairs. Further complications arise from a study of male stoat movements that become noticeably altered during the mating season. This coincides with a change in resource priority from food to females. So, how do mustelids maintain such diverse socio-biological systems, and what strategies are used in territorial defense? It is well known that mammals use ‘social odors’ extensively to convey messages, both intra- and inter- specifically and the Mustelidae are no exception. Understanding mustelid scent marking is important, as it constitutes their primary form of communication. 2. Scent marking in mustelids. Transmission of information between individuals is essential for the maintenance of the complex